The latest nuclear test, in September, is believed to have triggered a 6.2 earthquake followed by a series of other smaller quakes.

Kim Jong Un was willing to move mountains to develop his nuclear weapons, though doing so may have led to the stop in his testing program.

North Korea announced last weekend that it would no longer carry out missile or nuclear tests, with its leader saying that the quest for weapons of mass destruction was "complete."

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However, research by Chinese geologists suggests that the previous tests had caused the mountain above the main testing site to collapse, perhaps offering another motive for the apparent gesture of good faith.

North Korean leader Kim Jong Un is set to meet Friday with South Korean President Moon Jae-in. (KCNA VIS KNS/AFP/Getty Images)

Geologists at the University of Science and Technology of China said in a paper that an earthquake created an "onsite collapse toward the nuclear test center" shortly after the testing of a bomb in September with the force 100 kilotons worth of TNT.

Beyond the first 6.3 magnitude quake, the test, North Korea's sixth, is believed to have caused four more earthquakes in the following weeks.

Chinese scientists say that the mountain at a North Korean nuclear test site (administrative buildings pictured in November ) collapsed after a September test. (DigitalGlobe/ScapeWare3d/Getty Images)

The paper is slated for publication in Geophysical Research Letters, and looks at the problem of leaking radioactive material as well as the the nuke-triggered earthquakes that have caused evacuations on the other side of the nearby Chinese border.

Kim?s statement that his hermit kingdom would give up its headline-grabbing tests comes after rounds of sanctions were implemented by the international community including China, a crucial trading partner.

North Korea has said that it will stop nuclear and missile tests. (KCNA/REUTERS)

The strongman is set to meet Moon Jae-in, the president of South Korea, in a historic summit in the border village of Panmunjon this Friday that is expected to discuss denuclearization.

President Trump is also scheduled to meet with Kim, who has said that giving up nuclear weapons must be tied to U.S. troops leaving his southern neighbor, in late May or early June.